1. Field of the Invention
The present invention relates to an optical transceiver cage, and more particularly to a small form-factor pluggable (SFP) transceiver cage of a high data transfer rate program gigabit interface converter (GBIC).
2. Description of the Related Art
Transceiver modules provide bidirectional transmission of data between an electrical interface and an optical data link. The module receives electrically encoded data signals and converts them into optical signals which are then transmitted over the optical data link. The module also receives optically encoded data signals, converts them into electrical signals, and transmits the electrical signals to the electrical interface.
Normally, the transceiver module is mounted on a printed circuit board (PCB) assembly of a host computer, an input/output system, a peripheral device, or a switch. An SFP transceiver module connects with a metal cage assembly mounted on the PCB. The metal cage generally has two parallel sidewalls, a rectangular top, a rectangular bottom, and front and rear ends. The metal cage provides easy interconnection, and is easily installed on the PCB. The cage functions to dissipate electrostatic buildup, and serves as an electromagnetic shield.
A conventional cage forms legs for supporting the cage on the PCB, and a plurality of outwardly projecting grounding tabs adjacent an entrance of the cage for engaging with a grounding chassis. However, there are no structures specifically for ground contacting a housing of an SFP transceiver module which is secured in the cage. The cage does not provide adequate protection for the connecting interface from electromagnetic interference (EMI). In addition, there is no board locking mechanism to safeguard reflowing of solder during soldering of the cage to the PCB. The cage is liable to disengage from the PCB, causing poor soldering.
Accordingly, an object of the present invention is to provide an SFP transceiver cage which has a plurality of outward and inward grounding spring tabs to facilitate grounding and prevent EMI.
Another object of the present invention is to provide an SFP transceiver cage having legs that enable the cage to be locked on a PCB during soldering of the cage to the PCB.
A further object of the present invention is to provide a sturdy SFP transceiver cage that is easily and inexpensively made essentially from a single metal plate.
To achieve the above objects, an SFP cage in accordance with a preferred embodiment of the present invention comprises two sidewalls, a sidewall cover, a top plate, a bottom wall, a rear cover and an outer grounding plate. The sidewalls, sidewall cover, top plate, bottom wall and rear cover are collectively preferably made from a single piece of metal plate. The outer grounding plate has a plurality of outward grounding spring tabs. A plurality of inward grounding spring tabs formed on the top plate project into a central cavity of the cage for contacting a housing of an SFP module secured in the cage. The inward grounding spring tabs cooperate with the outward grounding spring tabs to provide multiple grounding paths and prevent EMI. A plurality of compliant legs, needle eye legs and support legs depends from the sidewalls. The compliant and needle eye legs are extended through corresponding holes defined in a PCB. The compliant and needle eye legs prevent the cage from moving relative to the PCB during the course of solder reflowing. The support legs abut a face of the PCB. The support legs serve as standoffs, separating the cage from the PCB to facilitate accurate soldering.
Other objects, advantages and novel features of the present invention will be apparent from the following detailed description of a preferred embodiment thereof with reference to the attached drawings, in which: